vThe response of human lung epithelial cells and endothelial cells to oxidative stress is being studied at the level of cellular function and gene expression. Signal transduction pathways activated in response to oxidative stress and linked to these events are also under active investigation. Oxidative stress induces necrosis in human lung epithelial cells. Similar levels of oxidative stress are not lethal to endothelial cells which respond with contraction and with production of gene expression in a variety of antioxidant proteins. One manuscript is in press.